mrwillie wrote:
I thought pyrolysis was done in a near air tight container w/ the o2 levels very low and controlled. Not just a burning container that vents to the atmosphere. Some of the tests that I have seen involve capturing the gas from the combustion process and condensing it somehow. Have you seen info where the emissions from these situations are high? Not having actually pulled the trigger myself and tried in my backyard, I can only go off of what I read. Can you explain it to me better? Maybe I misunderstood something.
I'm familiar with pyrolysis. I do permits on various units quite regularly. Really, they're just an incinerator. A starved air incinerator, but an incinerator none the less.
You can build a pyrolysis unit at home with a soda can. Take the soda can, stuff some wood chips down into it. Place it on a grill. It'll smoke like crazy, without actually burning. That's pyrolysis in a nutshell, woodchips in a soda can, baking on a fire. Makes charcoal by the way.
To make life exciting, soak the woodchips with bacon fat or such before placing them in the can. This is a real problem with lots of pyrolysis, contamination of the charge. Not only does one get smoke and fires and sometimes even explosions, but it's darn hard on the soda can, and the grill.
A bit less exciting, poke some holes in the can. Now your woodchips burn up, and you get no charcoal, just ash.
But wait, pyrolysis makers say there is no smoke. There is either sleight of hand, or they didn't tell you about that expensive secondary chamber. A secondary chamber is essentially an incinerator that you run the smoke from the first incinerator through. This secondary chamber is bigger and more expensive to fuel than the first incinerator.
Conventional smoke does burn in that secondary chamber, so you get little visible emissions. But, many of the nasties, particularly the metal nasties and the dioxin type nasties , go right on through. In fact, that secondary chamber that reduces the smoke and smells tends to drive the metals and dioxin emissions...up. Has to do with more thorough volatilization.
Sleight of hand? Surely I jest. I liked one that was for reacting, among other things, gunpowder. The system was going to be completely sealed, preventing any gasses from escaping. Gunpowder, heated until it ignites, in a perfectly sealed container. Sleight of hand. The army was very excited about this.
The latest pyrolysis wonder I'm dealing with is a magical unit that will produce drinking water and unlimited electricity from sewage. Seriously. They want to build a power plant to power the pyrolysis power plant, and somehow filling the pyrolysis chambers with human sewage and running electric arcs through it will create unlimited electricity and lots of fresh electricity for the town. They've already got a construction site and the town is convinced this is going to be nirvana (they do have water and sewage problems).
